Current ADSL modem system designs do not incorporate a low power transmission mode. Such systems require high power dissipation in the modem line driver, even when no data is being transmitted.
Accordingly, ITU contributions have proposed a low power mode (i.e., “Q-mode,”) in the transmitter. During the proposed Q-mode, the modem is still in the ready state, but enters a low power mode during periods of no data transmission.
One ITU contribution, HC-029R1, formally defines a semi-stationary Q-mode signal, that employs a pair of pseudo-random bit sequence (“PRBS”) generators, each with a period of greater than 4000. One problem with this proposal, however, is that the receiver would require synchronization to two PRBS generators. In addition, requiring two PRBS generators as such correspondingly requires additional hardware in the modem, as well as additional overhead associated with the overall system. Moreover, during the non-Q-mode periods of operation, i.e., during data mode or “SHOWTIME,” the two PRBS generators sit idle.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.